1. Field of the Invention
This invention relates to the field of design and construction of insulated transparent structures such as solar collectors, greenhouses, skylight and the like, and in particular to solar collectors adapted to be mounted on the roof of a structure and connected to a supply and discharge of a heat transfer fluid to be heated by the collector, the heat transfer fluid eventually discharging energy into a heat reservoir or an object or space to be heated.
2. Description of the Prior Art
The general idea of a solar collector mounted on a rooftop is well known. There are nevertheless many variations on the general idea. Collectors have been disclosed that collect heat using pipes to carry heat transfer fluid through an area heated by the sun, devices to flow heat transfer fluid over a heated surface, and even use of colored or otherwise darkened heat transfer fluid. The present invention relates to the construction and structural design of solar collectors and the like, rather than to a particular method of collecting.
Solar collectors available on the market are often pre-packaged to be merely positioned on the roof of a structure and attached. While such pre-packaged units are convenient for some applications, a problem is presented where a very large collector is contemplated. As one option, a builder might connect a series of smaller, pre-packaged solar collectors into a larger system. Alternatively, the builder must assemble an entire solar collector panel at the job site. Inasmuch as the assembly must be conducted at least partly by workmen dangling from ladders, scaffolds, etc., usually on sloping rooftops, the finished product often leaves much to be desired.
Solar collectors are regularly exposed to exceedingly harsh conditions while in use. The structure and heat-collecting apparatus are exposed to scorching temperatures in the daytime, and freezing temperatures at night, often during the same 24 hour period. Different materials in the collector structure expand and contract differently during temperature cycling, gradually opening up the joints. Rain will fall and ice will freeze on the solar collectors and minor inadequacies in construction will permit the natural elements to gradually wear away and ruin the collector, moisture leaking into the collector from outside, and seals and connections gradually coming apart.
From the inside, in collectors employing water as a heat transfer fluid, calcium and other scale deposits precipitate on internal surfaces and eventually impede or obstruct fluid flow. Any liquid leaking fom the internal fluid passages tends to compound the problem of fluid leaking in from outside. As fluid in the interstices is heated and cooled, joints are stressed. Inasmuch as substantial temperature cycling is encountered by the device in use, the entire collector will deteriorate in a relatively short time, often before the unit has paid for itself in terms of fuel savings, unless great care is taken to make the unit structurally strong.
Accordingly, there has been a need for a solar collector construction system and apparatus that will allow even a large solar collector to be very solidly and tightly constructed on the site, yet provides all the advantages of increased efficiency that the art can provide. Since solar collectors have become popular, new installations appear frequently. Where a large structure is intended to be heated by a solar collector, or where substantial backup heating capability is desired, a system for solidly constructing such large solar collector devices will fill a need that is not adequately met by smaller integral units daisy-chained together or by larger units haphazardly constructed.